Magnetic switch



Oct. 7, 1958 Filed April 16, 1956 H. E. COBB ETAL MAGNETIC SWITCH 2Sheets-Sheet 1 IN VEN T0165 flw BY 696*? W ,Oct. 7, 1958 H. E. COBB ETAL2,855,482

MAGNETIC SWITCH 2 Sheets-Sheet 2 Filed April 16. 1956 BY 06% mm A rroRIVEYS.

Me/wim/ 3w Patent 55$ 2,855,482 Patented Oct. 7, 1958 2,855,482 MAGNETICSWITCH Harold E. Cobb, Batavia, and Paul F. White, Glen lillyn,

Ill., assignors to Furnas Electric Company, Batavia, Ill., a corporationof Illinois Application April 16, 1956, Serial No. 578,288

7 Claims. (Cl. 200--104) The present invention relates generally toimprovements in magnetic switch assemblages, and it relates moreparticularly to improvements in the construction and operation ofelectro-magnetically actuated switches adapted to function in uprightposition.

The principal object of our invention is to provide various improvementsin the construction of magnetically actuated switches whereby theefiiciency and utility thereof is materially enhanced while the cost ofconstruction is reduced to a minimum.

Some of the more important specific objects of the present invention areas follows:

To provide a sturdy magnetic switch which is simple but durable inconstruction and which is also exceptionally quiet and reliable inoperation.

To provide an improved electro-magnetically actuated switch assemblageof the type wherein the circuits are closed by magneto-motive force andare opened by gravity acting upon a vertically reciprocable magneticarmature.

To provide an improved mounting and enclosure for a magnetic switchmechanism which is flexible in its cooperation with various types ofelectric control systems, and wherein all parts are normally wellconcealed and protected but are also conveniently accessible forinspection and wiring installation.

To provide an improved magnetic switch and thermal overload unit whereinthe various parts are amply protected against damage due to excessivecurrent but may be quickly reset to function normally when the dangerouscondition has been eliminated.

To provide an improved coil and magnet assembly for a magnetic switch,which may be produced at moderate cost by utilizing relatively fewstandard parts effectively cooperating with simplified motion transferelements for the movable contacts.

To provide improvements in the magnet and control switch supports of amagnetic switch, and in the mechanism for transferring the movement ofthe magnet armature to the switch contacts so as to eliminate noise andvibration.

To provide an improved stationary contact and terminal.

support for a poly-phase magnetic switch, and means for effectivelyinsulating the various parts of such an assemblage.

To provide an improved magnetic switch and housing assemblage manyelements of which may be readily constructed of sheet metal with the aidof punches and dies, and durably united with self locking fasteners toproduce a sturdy final unit.

These and other more specific objects and advantages of our inventionwill be apparent from the following detailed description.

A clear conception of the various features constituting the presentimprovements, and of the construction and operation of a commercialmagnetic switch embodying the invention, may be had by referring'to thedrawings accompanying and forming a part of this specification 2 whereinlike reference characters designate the same or similar parts in thevarious views.

Fig. 1 is a front elevation of a magnetic switch assemblage having apush-button control switch applied thereto but with the major portion ofthe casing cover broken away in order to reveal normally enclosed parts;

Fig. 2 is a vertical section through the magnetic switch unit of Fig. 1,taken along the line 2-2;

Fig. 3 is a central longitudinal section through one of the improvedthermal overload devices associated with the switch assemblage of Figs.1 and 2, the section having been taken along the line 3-3 of Fig. 1;

Fig. 4 is a front elevation of the magnet and contact portion of thesame switch assemblage, but with the push button control switch omitted;

Fig. 5 is a fragmentary side view of a pair of the movable contacts andof the pusher and guide elements therefor;

Fig. 6 is an enlarged plan view of the upright magnet and are boxsupport;

Fig. 7 is a side view of the support shown in Fig. 6; and

Fig. 8 is an end view of the same support.

While the invention has been shown and described herein as having beenembodied in a commercial magnetic switch having four cooperating sets offixed and movable contact, two thermal overload devices, and a pushbutton control switch all incorporated in the same switch assemblage, itis not intended to restrict the use of theimproved features to such aunit; and it is also contemplated that specific descriptive termsemployed herein be given the broadest possible interpretation consistentwith the disclosure.

Referring to the drawings, the electro-magnetically actuated switchdisclosed therein comprises in general, a

casing consisting of a rear mounting section 10 and a front closuresection 11; an upright main support 12 detachably suspended in-thecasing section 10; an arc box or fixed contact housing board 13 securedto the upper end of the support 12 and having therein four sets ofstationary contacts 14; a magnetic field piece 15 secured to a lowerportion of the support 12 and embracing an energizing coil 16; amagnetic armature 17 reciprocable vertically within the magnet coil 16,and having a lower end projection 18; a pusher 19 surrounding the fieldpiece 15 and having an end flange 20 pivotally attached to the armatureprojection 18, while its upper end 21 spans the top of the field piece15 and is connected to a transverse cross-bar 22 which carries four setsof movable contacts 23 adapted to cooperate with the stationary contacts14; a fixed guide plate 24 for the pusher 19 clamped between the support12 and the arc box 13; a thermal overload device 25 fastened to thesupport 12 on each side of the magnet assemblage; and a pushbuttoncontrol switch 26 secured to the front face of the field piece 15, seeFigs. 1 and 2.

The sections 10, 11 of the main switch housing casing may be formed ofsheet metal, and the mounting section 10 has a fiat base provided withthe usual suspension openings 28 and has upper and lower forwardlyextending flanges 29, 30, while the closure section 11 has a fiat frontmerging along curved portions into rearwardly extending opposite sideflanges 31. The two sections 10, 11 may be firmly but detachablyinterconnected by screws 32, and when these casing sections areseparated they leave the opposite sides of the normally concealed switchassemblage unobstructed for free attachment of the conductor terminals,but when united the cooperating sections 10, 11 thoroughly conceal andprotect the mechanism.

The main magnet and are box support 12 may. also be formed of sheetmetal, and is detachably attachable to the flat base of the casingsection 10 by means of a tongue 34 formed integral with this section 10and which hooks over the lower medial edge portion 35 of the support 12,and also by screws 36 secured to. the casing base and which coact withupper side openings 37 formed in the support, see Figs. 1, 2, 6, 7 and8. The central portion of the support 12 is provided; Withz a. F-shaped.open ing 35 within which an auxiliary sheettrnetali supporting;

pad 39 is rigidly secured as by welding, and this pad139 has severaloutwardly projecting integral lugs: 40: ten properly positioning thefield piece 15,, and isi alsoprovided with upper side flanges 41 towhich: the; arc box13s and the guide plate 24 are firmly attachedclamping screws 42, as shown in Fig. 2. The upperend of thezpad.

39 is moreover provided with a central projection 43 and with two sideprojections 44' asshown-in Figs. 6, 7' and 8,. which serve to accuratelyposition thearc box. 13. relative:

to the magnet assemblage.

The arcbox or fiXedT contact housing 13. is formed of mouldedinsulatiom, and may be provided. with either four or a lesser numberofsetsof fixed contacts 14 de-' pending upon the purpose for which, theswitch assemblage is to be used. The contacts 14 are secured. to upperand lower metal terminals 46, 47 respectively, each having a-conducto-rattachingscrew-48 applied thereto at the front of the box 13, and eachof the upper terminals 46 may be provided with an integral'upwardlyprojection 49 having an auxiliary conductor attaching screw 56associated therewith,- see Figs. 1 and 2. The lower terminal 47 may alsobe provided with an integrallug 51 adapted to be embeddedv in the arcbox 13- as in Fig. 2 in order to firmly hold the adjacent contacts 14 inposition, and they other contacts 14- are so held by passing. the. upperterminals 46 through slots 52 in the box.

The magnet unit comprising the field piece 15, coil 16,

armature17, guides 54, and conductor attaching screws 55, is ofrelativelyv standard commercial construction, and the field piece andarmature 17 arembothformed of metal laminatio-ns, the armature 17 beingelevated by energization of the coil 16 and descending by gravity whenthe coil is de-energized to thusclose and open the; electric circuitthrough the switch. However, the means for transmitting thereciprocation of. the armature 17 to the movable contactslS'. in a quietand positive manner, is

an important feature of the present improvement, and this mechanismcomprises the O-shaped sheet metal pusher 19 which loosely surrounds thefield piece 15 and-the coil 16 and has its lower endprovided with theflange 2t) pivotally attached to the lower armature end projection 18while its upper horizontal end 21bridgesthe topof the.

field piece 16.

The pusher 19 is formed. asillustrated in.Figs..4 and 5, and the lowerpusher flange 20. provides a loop within which an insulating bushing 57embracing a pivot pin 58, is confined. The pivotpin coacts with thearmature guides 54 and is held in place by insulating washers59, so thatthe pusher 19 is thoroughly insulated from the armature 15. The pusher19 moreover does not contact any portion of the field piece 15; but has.its upper portion guided by the plate 2.4 which is formed. of.insulation and spans the interior of the pusher 19 above the field piece15 and beneath the upper bridge portion 21-, thus also thoroughlyinsulating the pusher 19-from the field piece 15 and coil 16. The centerpart of the pusher portion 21 is provided with an outwardly projectingintegral lip 60 which is engageable with the guide plate 24 to limit theopening movement of the movable contacts 23, and

the contact carrier bar 22 is secured to the pusher 19by" screws 61.

The guide plate 24 has opposite side grooves: within which the oppositesides of the pusher 19 are rather snugly but freely slidably confined,and this plate 24 coop. erates with the armature guides 54 toconfine thearmature 17, the pusher 19 and the contact carrier bar 24 to rectilinearmotion. The bar 24 is formed of insulation and the movable contacts 23are mounted upon cross: conductors 63 which are slidable along guideposts 64 and are constantly urged against lateral stops at the upperends of these posts by helical compression springs 65 in a well knownmanner. Each set of cooperating fixed and movable contacts 14, 15 ishoused within a cavity in the arc box 13 which is segregated fromadjacent cavities by integral division walls 66 so as to positivelyprevent objectionable arcing.

The improved thermal overload devices 25 may be mounted upon the mainsupport 12 on the opposite sides of the magnet assembly by means. ofscrews coacting with openings 68 in the. support and with the baseplates 69 of the overload units, and these thermal overload devices arespecially constructed to cooperate with the present improved uprightmagnetic switches. As shown in Fig. 3, each of theoverload devicescomprises a body 70 secured to the base 66 and having laterally spacedfixed contacts 71 mounted therein; a reset plunger 72 slidable withinthe body 70 by an actuator 73, and carrying movable contacts 74cooperable with the adjacent fixed contacts 71; a solder pot 75:mo.untedcentrally within the'body 70 and cooperating with; a ratchet 75 and witha heating element 76;. and a spring 77' normally urging the plunger 72toward the actuator 73.

The actuators 73 are disposed horizontally and are normallyurgedoutwardly so-as to protrude from the casing cover 11 as in Fig. 2,by springs 78, and they are slidable within the adjacent bodies 70 atright angles to the direction of sliding of the adjacent plungers 72.The adjacent ends of each actator 73 and plunger 72. are disposed atlike angles relative to each other so that by depressing an actuator 73it willmove. the adjacent plunger 72 inwardly against: the spring 77 toactuate the corresponding ratchet 75 andv reset the device 25. Theopposite ends of each heating element 76 are connected toterminalplates' 79'adapted to be applied to the electrical systemv by.conductor attaching screws 80', and the fixed and movable contacts 71,74 may be likewise applied by screws 81.

The starting and stopping switch 26 which is shown as being. of thepushbutton type, may be of any other suitable type adapted to manuallymake and break the main electric circuit. This switch 26 is mounted upona plate 83 secured by one or more screws 84 to a sheet metal bracket'8'5which may be attached to the field piece 15 of the magnet by a cotterpin 86 orthelike. The push buttons 87, 88 of the switch 26-are exposedfor manual operation through another opening in the casing cover 11, butthe switch 26 must be Well insulatedfrom the magnet assembly in order toavoid short circuiting of the electrical system. The improved magneticswitch assemblage may be installed in numerous types of electricalsystems for diverse purposes well known to the users of such equipment,and the various attaching screws are preferably formed or provided withlock washers or the like so that they cannot become detached duringnormal operation.

When the improved magnetic switch and thermal overload unit has beenproperly constructed, assembled and installed in an electrical controlsystem for a motor or the like, the system may be manually placed inoperation by merely depressing thestarting button 87 of the switch 26.The magnet, coil 16 will then be energized to cause the field piece 15to lift the armature 17, thereby elevating the pusher 19 and the crossbar 22 and engaging the movable contacts 23 with the fixed contacts 14and closing the main circuit. Thiscircuit will thereafter remain closedeither until the stop button 88. is manually depressed, or

in case'of an overload. In either case the magnetcoil 16' will then bede-energized. and the armature 17 will promptly'drop by gravity to lowerthepusher 19 and the cross bar 22 and to thus move the contacts 23 outof engagement with the fixed contacts 14.

If the main circuit has been thus interrupted by an overload condition,the contacts 71, 74 of the overload devices 25" will have beenseparatedby the springs 77 sliding the, plungers 72 upwardly against theinclined inner.

assaasa ends of the actuators '73; and after the solder pots 75 havecooled fdue to cooling ofi of the heating elements 76 which functionedto interrupt the circuit, the devices 25 must be reset. This may readilybe done by depressing the actuators 73 to push the plungers 72 inwardlyagainst the springs 77 sufliciently to cause the movable contacts 74 toagain engage the fixed contacts 71, whereupon the ratchet 75' willfunction to retain the overload devices 25 in active condition untilsubsequent overloading of the main circuit occurs.

From the foregoing detailed description of the construction andoperation of the typical magnetic switch it will be apparent that thepresent invention in fact provides a simple, compact and durable uprightswitch assemblage which is extremely'reliable and positive in operation.All parts of the improved switch are well insulated and amply protectedagainst short circuiting and dangerous arcing, and all of the conductorattaching portions of the as- :semblage as well as the more delicatemechanisms are conveniently accessible whenever desired by merelysepsarating the housing sections 10, 11 with the aid of a screw driver.While the cover section 11-is thus readily re- .movable for inspectionand installation purposes, the mounting section may also be convenientlyremovably :attached to a support with the aid of screws applied to theopenings 28.

The improved pusher 19 for transmitting movement of the armature 17 tothe cross-bar 22 and movable contacts 23, not only insures positive andrapid actuation of the switch, but also does so quietly and with minimumshock. The forwardly projecting lug 60 on the upper transverse portionof the pusher positively arrests the opening movement of the contacts 23and armature 17, and the guide plate 24 effectively cooperates with theguides 54 to most accurately produce true rectilinear movement of thearmature 17 and of the movable contacts 23. The main support 12 with itsmounting bracket 39 for the magnet, as well as the pusher 19 and casingsections 10, 11 may be readily fabricated from sheet metal with the aidof punches and dies, and the stop lugs 43 on the support 12 providethree point mounting pads for properly positioning the arc housing 13.

The improved thermal overload devices 25 are also especially adapted foruse in conjunction with the improved upright magnetic switch, sincethese devices may be nested closely adjacent to the magnet and mountedupon the magnet support 12 with their actuators 73 horizontally disposedand protruding through the casing cover 11 for convenient manipulation.The actuators 73 are adapted to quickly and eifectively reset thedevices 25, and the entire switch assembly has proven highlysatisfactory and successful in actual use and can be produced .forvarious uses at very moderate cost.

It should be understood that it is not desired to limit this inventionto the exact details of construction or to the precise mode of operationof the magnetic switch assemblage herein specifically shown anddescribed, for various modifications within the scope of the appendedclaims may occur to persons skilled in the art.

We claim:

1. In a magnetic switch, a support, a stationary contact secured to oneend portion of said support, a magnetic field piece mounted upon theopposite end portion of said support, an energizing coil confined withinsaid field piece, a magnetic armature cooperable with said field pieceand having guides reciprocable within said coil, a unitary pushersurrounding but spaced from said field piece and said coil and havingone end provided with an integral lateral flange pivotally secured tobut insulated from said armature while its opposite end spans the fieldpiece, a movable contact carried by said spanning pusher end and beingcooperable with said stationary contact to make and break an electriccircuit, and a guide plate coacting with said pusher beyond said fieldpiece and closely adjacent to said contacts.

2. In a magnetic switch, a support, a stationary contact secured to oneend portion of said support, a magnetic field piece mounted upon theopposite end portion of said support, an energizing coil confined withinsaid field piece, a magnetic armature reciprocable toward and away fromsaid contact and said field piece, a unitary annular pusher surroundingsaid field piece and said coil and having one end pivotally secured tothe projecting end of said armature while its opposite end spans thefield piece, a movable contact carried by said spanning pusher end andbeing cooperable with said stationary contact to make and break anelectric circuit, and a guide plate for said Pusher interposed betweensaid field piece and said contacts closely adjacent to the latter, saidspanning pusher end having thereon an integral laterally projecting stopcooperable with said guide plate to limit the contact opening movementof said armature.

3. In a magnetic switch, an upright support, a stationary contactsecured to an upper portion of said support, a magnetic field piecemounted upon a lower portion of said support, an energizing coilconfined within said field piece, a magnetic armature verticallyreciprocable relative to the bottom of said field piece, a unitaryannular pusher loosely surrounding said field piece and said coil andhaving its lower end secured to the corresponding end of said armaturewhile its upper end spans the top of the field piece, a movable contactcarried by said upper pusher end and being cooperable with saidstationary contact to make and break an electric circuit, and aninsulating pusher guide interposed between said field piece and saidupper pusher end closely adjacent to said contacts, said upper pusherend having thereon an integral laterally projecting stop cooperable withsaid guide to arrest the downward travel of said movable contact.

4. In a magnetic switch, a support, a stationary contact carried by saidsupport, a magnetic field piece mounted upon said support and havingtherein an energizing coil, a magnetic armature reciprocable relative tosaid field piece, a continuous sheet metal pusher surrounding but spacedfrom the opposite sides of said field piece and said coil and having oneend pivotally secured to but insulated from said armature while itsopposite end spans the field piece, and a movable contact carried bysaid spanning pusher end and being cooperable with said stationarycontact to make and break an electric circuit.

5. In a magnetic switch, a support, a stationary contact carried by saidsupport, a magnetic field piece mounted upon said support and havingtherein an energizing coil, a magnetic armature reciprocable relative tosaid field piece, a unitary resilient pusher surrounding but spaced fromthe opposite sides of said field piece and said coil and having one endpivotally secured to said armature while its opposite end spans thefield piece, a movable contact carried by said opposite pusher end andbeing cooperable with said stationary contact to make and break anelectric circuit, and a guide plate for said pusher interposed betweensaid field piece and said contacts closely adjacent to the latter, saidopposite pusher end having thereon a laterally projecting integral stopcooperable with said plate.

6. In a magnetic switch, an upright support, a stationary contactcarried by said support, a magnetic field piece mounted upon saidsupport and having therein an energiz ing coil, a magnetic armaturevertically reciprocable beneath and relative to said coil, a unitarysheet metal pusher having fiat upper and lower ends and opposite sideslying in a common plane and loosely surrounding said field piece andalso having its lower end provided with an integral lateral flangesecured to but insulated from the corresponding end of said armaturewhile its upper end extends horizontally across the top of the fieldpiece and is provided with an integral lateral stop, a movable contactcarried by said upper pusher end and being cooperable with saidstationary contact to make and break an electric circuit, and aninsulating pusher guide interposed between said field piece and saidhorizontal pusher end closely adjacent to said stop.

7. In a magnetic. switch, an upright'support, a stationary contactcarried by an upper portion of said support, a magnetic field piecemounted upon a lower portion of said support and having therein anupright guideway, a magnetic armature having parallel central guidesvertically reciprocable Within said guideway, aunitary sheet metalpusher having flat upper and lower ends and' opposite sides lying in acommon plane and loosely surrounding said field piece and said coil andhaving its lower end provided with an integral lateral projection flangeswingably attached to thei'corresponding end of said armature While itsupper end spans the top of the field piece and is providedwith anintegral stop, a movable contact carried by said upper pusher end andbeing eooperable with said stationary contact to make/and break anelectric circuit, and an insulating pusher guide secured to. the upperend of said support and cooperating. with said pusher sides closelyadjacent to. saidlcontacts to confine said pusher to rectilinearmovement.

References Cltedlin the file-of this patent UNITED STATES PATENTS2,064,632 Schmitt Dec. 15, 1936 2,087,895 Bierenfeld July 27, 19372,094,199 Werner Sept. 28, 1-937 2,172,633 Wilms: Sept. 12, 19392,310,056- Bendz Feb. 2, 1943 2,347,934 Christensen et al. May 2, 19442,378,022 Logan June 12, 1945 2,687,458 Cobb et al. Aug, 24, 19542,687,502 Furnas. et aL Aug. 24, 1954 2,721,963 Knight. Oct. 25, 1955

